Buyer Address Missing on Refunds

I have a problem with a particular client when downloading transactions (using GetSellerTransactions with the DetailLevel set to All) that have been refunded. In some, but not all cases, the buyer name and address (with the exception of the postcode) is not being returned by the API and is missing from the XML.

Having looked at the transactions in question there appears to be no consistency, i.e. the transactions with no address appear to be no different to others that have been refunded but do show an address.